The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
FIG. 1 illustrates a conventional wireless communication system 10 including a first wireless device 12 that communicates with a second wireless device 14 via a channel 16. The first wireless device 12 includes a transmitter 18 and a receiver 22. The transmitter 18 may transmit radio-frequency (RF) signals via antennas 20-1, 20-2, . . . , and 20-n (collectively antennas 20). The receiver 22 may receive RF signals via the antennas 20. The second wireless device 14 includes a receiver 24 and a transmitter 28. The receiver 24 may receive RF signals via antennas 26-1, 26-2, . . . , and 26-n (collectively antennas 26). The transmitter 28 may transmit RF signals via the antennas 26. The transmitter 18 may communicate with the receiver 24 via the antennas 20, 26. The transmitter 28 may also communicate with the receiver 22 via the antennas 20, 26. For example only, the first and second wireless devices 12, 14 may include wireless access points (e.g., a wireless router) and wireless adapters (e.g., a wireless network interface card).
The transmitter 18 may encode data streams for transmission via the antennas 20. The antennas 20 transmit signals based on the data streams. A signal transmitted based on a single data stream is referred to herein as a “single stream signal.” When the transmitter 18 transmits a single stream signal, the transmitter 18 operates in a “single stream mode.”
Additionally, the antennas 20 may transmit signals based on multiple data streams. For example, a first set of the antennas 20 may transmit a first single stream signal, and a second set of the antennas 20 may transmit a second single stream signal. Signals transmitted based on multiple data streams are referred to herein as “multi-stream signals.” Transmitting multi-stream signals over the channel 16 may be referred to as “spatial multiplexing”. When the transmitter 18 transmits multi-stream signals that correspond to multiple data streams, the transmitter 18 operates in a “multiple-input multiple-output (MIMO) mode.”
The transmitter 18 may selectively operate in the single stream mode or the MIMO mode. When operating in the single stream mode, the transmitter 18 may comply with at least one of the Institute of Electrical and Electronics Engineers (IEEE) standards including IEEE 802.11a, IEEE 802.11b, and IEEE 802.11g, which are incorporated herein by reference. When operating in the MIMO mode, the transmitter 18 may comply with standards including The 3RD generation partnership project (3GPP™), IEEE 802.16e, and IEEE P802.11n™/D3.00 (hereinafter “802.11n”), which are incorporated herein by reference.